Gasification furnace apparatus

ABSTRACT

Provided is a gasification furnace apparatus equipped with a supply source of low-oxygen-concentration drying gas that does not require fuel. A coal pulverizer that produces pulverized coal by pulverizing coal, an air separator that separates air into oxygen gas and nitrogen gas, and a gasification furnace that produces product gas by introducing thereinto the pulverized coal and the oxygen gas, are included. By receiving a supply of excess nitrogen gas from the air separator, the air diluted with nitrogen is used as a source of low-oxygen-concentration gas for drying the pulverized coal, and an air heater that heats the source of low-oxygen-concentration gas to a temperature at which drying can be performed is provided.

RELATED APPLICATIONS

This application is a national phase of PCT/JP200965078, filed Aug. 28,2009, and is based on, and claims priority from, Japanese ApplicationNumber 2008-229520, filed Sep. 8, 2008.

TECHNICAL FIELD

The present invention relates to a gasification furnace apparatus thatis applied to, for example, a chemical gasification furnace thatproduces product gas for chemical synthesis from pulverized coal.

BACKGROUND ART

In addition to a chemical gasification furnace that produces product gasfor chemical synthesis, known gasification furnace apparatuses thatproduce gas using pulverized coal as raw material include, for example,gasification furnaces that produce fuel gas for gas turbines used atintegrated gasification combined cycle power plants (for example, seePatent Literature 1).

In a conventional gasification furnace apparatus G shown in FIG. 3,pulverized coal obtained by pulverizing coal, which is the raw material,with a coal pulverizer 1 is supplied to a gasification furnace 2. At thegasification furnace 2, product gas, which is gasified pulverized coal,is produced by receiving a supply of nitrogen and oxygen from an airseparator 3, in addition to the pulverized coal.

Note that, at the coal pulverizer 1, drying gas is required whenproducing the pulverized coal; therefore, for example, as in thegasification furnace apparatus G shown in FIG. 3, the drying gasrequired for pulverized coal production is obtained by providing acombustion furnace 4 or the like.

CITATION LIST Patent Literature

-   {PTL 1} Japanese Unexamined Patent Application, Publication No. Sho    61-175241.

SUMMARY OF INVENTION Technical Problem

Incidentally, in the conventional gasification furnace apparatus Gdescribed above, when using generally highly pyrophoric, low-grade coal,for example, subbituminous coal, brown coal, and so on, as raw material,the oxygen concentration of the drying gas is controlled at or below 13vol % to prevent spontaneous combustion.

In an air-blown integrated gasification combined cycle power generator,gas turbine exhaust gas having an oxygen concentration of 12 vol % isused as the drying gas described above. In this case, the temperature ofthe gas turbine exhaust gas used as the drying gas is adjusted to anoptimal temperature by mixing it with exhaust gas at an exhaust-gasboiler inlet/outlet.

In addition, in an oxygen-blown gasification furnace apparatus thatproduces product gas for chemical synthesis, there in no suitable sourceof low-oxygen-concentration gas for the drying gas; therefore, forexample, in the combustion furnace 4 shown in FIG. 3, fuel such asdiesel, natural gas, or the like is combusted to generate combustiongas. That is, the combustion furnace 4 is required for the chemicalgasification furnace, and the combustion gas generated at thiscombustion furnace 4 is used as high-temperature,low-oxygen-concentration drying gas. However, because generating thecombustion gas using the combustion furnace 4 requires fuel to producelow-oxygen-concentration drying gas, it is disadvantageous in terms ofrunning costs.

Against such a background, with a gasification furnace apparatusequipped with a coal pulverizer that obtains pulverized coal bypulverizing low-grade coal, it is desirable to have a supply source oflow-oxygen-concentration drying gas that requires no fuel.

The present invention has been conceived in light of the above-describedcircumstances, and an object thereof is to provide a gasificationfurnace apparatus equipped with a supply source oflow-oxygen-concentration drying gas that requires no fuel.

Solution to Problem

The present invention employs the following solutions in order to solvethe above-described problems.

A gasification furnace apparatus according to an aspect of the presentinvention includes a coal pulverizer that produces pulverized coal bypulverizing coal; an air separator that separates air into oxygen gasand nitrogen gas; and a gasification furnace into which the pulverizedcoal and the oxygen gas are introduced to produce product gas, wherein,by receiving a supply of excess nitrogen gas from the air separator, theair diluted with nitrogen is used as a source oflow-oxygen-concentration gas for drying the pulverized coal, and aheater that heats the source of low-oxygen-concentration gas to atemperature at which drying can be performed is provided.

In the gasification furnace apparatus described above, the coalpulverizer that produces the pulverized coal by pulverizing coal, theair separator that separates air into oxygen and gas, and thegasification furnace that produces the product gas by introducing thepulverized coal and the oxygen gas, and nitrogen gas are provided; byreceiving the supply of excess nitrogen gas from the air separator, airdiluted with nitrogen is used as the source of low-oxygen-concentrationgas for drying the pulverized coal; and the heater that heats the sourceof low-oxygen-concentration gas to the temperature at which drying canbe performed is provided. Therefore, by effectively using the existingdevices, the low-oxygen-concentration gas for drying the pulverized coalcan be obtained without requiring fuel.

In the gasification furnace apparatus described above, the heaterpreferably performs heat exchange between the vapor whose temperature israised upon passing through the gasification furnace and the source oflow-oxygen-concentration gas to achieve the temperature at which dryingcan be performed; accordingly, the temperature of the source oflow-oxygen-concentration gas can be raised to a temperature at whichdrying can be performed by effectively using the heat held by thegasification furnace.

In the gasification furnace apparatus described above, the heaterpreferably is the gasification furnace, which raises the temperature ofthe excess nitrogen gas that passes therethrough; accordingly, becauseair is consequently diluted by the high-temperature excess nitrogen gas,the temperature of the source of low-oxygen-concentration gas can beraised to a temperature at which drying can be performed by effectivelyusing the heat held by the gasification furnace.

Advantageous Effects of Invention

According to the present invention described above, by effectively usingthe excess portion of nitrogen gas generated in the air separator foruse in the gasification furnace and by effectively using heat held bythe gasification furnace in addition thereto, it is possible to obtainlow-oxygen-concentration gas for drying pulverized coal, which requiresno fuel for obtaining combustion gas. As a result, in a gasificationfurnace apparatus, such as a chemical gasification furnace, etc.equipped with a coal pulverizer that obtains pulverized coal bypulverizing highly pyrophoric, low-grade coal, thelow-oxygen-concentration drying gas, which is required when producingthe pulverized coal, can be obtained without providing a combustionfurnace that generates combustion gas using fuel.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram showing an embodiment of agasification furnace apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a modification of thegasification furnace apparatus shown in FIG. 1.

FIG. 3 is a configuration diagram showing a conventional gasificationfurnace apparatus.

DESCRIPTION OF EMBODIMENTS

An embodiment of a gasification furnace apparatus according to thepresent invention will be described below on the basis of the drawings.

A gasification furnace apparatus Ga shown in FIG. 1 is an oxygen-blownchemical gasification furnace that produces product gas for chemicalsynthesis, using generally highly pyrophoric, low-grade coal, forexample, subbituminous coal, brown coal, and so on, as raw material.

The illustrated gasification furnace apparatus Ga is provided with acoal pulverizer 1 that produces pulverized coal by pulverizing coal,such as low-grade coal, etc.; an air separator 3 that separates air intooxygen (O₂) gas and nitrogen (N₂) gas; and a gasification furnace 2 thatproduces product gas by introducing the pulverized coal produced by thecoal pulverizer 1 and the oxygen gas and nitrogen gas separated at theair separator 3.

The coal pulverizer 1 is a device that uses highly pyrophoric, low-gradecoal as raw material and produces pulverized coal by pulverizing the rawmaterial in an environment into which low-oxygen-concentration dryinggas has been introduced. The low-oxygen-concentration drying gas usedhere has a low oxygen concentration, at or below 13 vol %, and a highgas temperature of about 200 to 350° C.

The gasification furnace 2 is an oxygen-blown furnace into which thepulverized coal, oxygen gas, and nitrogen gas are introduced andproduces product gas by combusting the pulverized coal. Note that,nitrogen gas is introduced into the gasification furnace 2 only whenneeded.

The air separator 3 is a device into which air is introduced from theatmosphere, that separates it into oxygen gas and nitrogen gas, and thatsupplies them to the gasification furnace 2.

The above-described coal pulverizer 1 requires low-oxygen-concentrationgas for drying the pulverized coal and, by receiving a supply of excessnitrogen gas from the air separator 2, uses air diluted with nitrogen asthe source of this low-oxygen-concentration gas. Because the air usedhere is introduced from the atmosphere, the temperature thereof is low,and moreover, to be used as drying gas, the temperature of excessnitrogen gas is also low. As a result, with regard to thelow-oxygen-concentration drying gas, which is the air diluted with theexcess nitrogen gas, the temperature thereof needs to be increased to adesired temperature to be suitable for drying gas.

Therefore, the gasification furnace apparatus Ga is provided with an airheater 5 as a heater for raising the temperature of the drying gas. Thisair heater 5 is a heat exchanger that performs heat exchange between thedrying gas at the source of the low-oxygen-concentration gas in whichthe air and the excess nitrogen gas are mixed at a desired proportionand the vapor whose temperature is raised upon passing through thegasification furnace 2, to thereby raise the temperature of the dryinggas. In the illustrated configuration, a heat exchange portion 2 a ofthe gasification furnace 2 absorbs heat, and the heat is radiated at aheat exchange portion 5 a of the air heater 5. Note that, with regard tothe vapor used at the air heater 5 for heating, the supply sourcethereof is not particularly limited.

In the thus-configured gasification furnace apparatus Ga, becauselow-oxygen-concentration air diluted with the excess nitrogen gas, whosesupply is received from the air separator 3, is used as the source ofthe low-oxygen-concentration gas for drying the pulverized coal and,furthermore, because the air heater 5 that heats thelow-oxygen-concentration drying gas with the vapor whose temperature israised with the heat held by the gasification furnace 2 is provided, byeffectively using the gasification furnace 2 and the air separator 3,which are existing devices, the low-oxygen-concentration gas for dryingthe pulverized coal can be obtained without requiring fuel consumption.

That is, because the air heater 5 heats the low-temperature drying gasto the temperature at which drying can be performed, without combustingfuel, by performing heat exchange between the vapor whose temperature israised upon passing through the gasification furnace 2 and thelow-temperature drying gas, high-temperature drying gas can be obtainedby effectively using the heat held by the gasification furnace 2. Inother words, because the excess nitrogen gas generated at the airseparator 3 is effectively used for diluting the oxygen concentration ofthe air and, furthermore, because heat generated at the gasificationfurnace 2 due to production of the product gas is effectively used forraising the temperature of the drying gas, the air heater 5, which is asimple heat exchanger that consumes no fuel, can be employed instead ofthe combustion furnace 4 that generates combustion gas, which serves ashigh-temperature low-oxygen-concentration drying gas, by consuming fuel.

Next, a modification of the embodiment of the above-describedgasification furnace apparatus Ga will be described on the basis of FIG.2. Note that, the same reference signs are given to the portions similarto the above-described embodiment, and a detailed description thereofwill be omitted.

In a gasification furnace apparatus Gb of the modification shown in FIG.2, instead of the air heater 5 that uses the vapor as a heating medium,serving as the heater for raising the temperature of the drying gas to adesired temperature at which drying can be performed, the excessnitrogen gas supplied from the air separator 3 is guided to thegasification furnace 2, and the excess nitrogen gas is directly heatedby the heat held by the gasification furnace 2 to raise the temperaturethereof. That is, the heater in this case is the gasification furnace 2that raises the temperature of the excess nitrogen gas that passestherethrough, and the oxygen concentration in the air is diluted withthe nitrogen by mixing the high-temperature excess nitrogen gas and thelow-temperature air; therefore, the temperature of thelow-oxygen-concentration gas can be raised to the temperature at whichdrying can be performed by effectively using the heat held by thegasification furnace 2. In other words, the gasification furnace 2 isconfigured to include a heat exchange portion 2 b for heating the excessnitrogen gas.

In the thus-configured gasification furnace Gb, the excess nitrogen gasgenerated at the air separator 3 is effectively used for diluting theoxygen concentration of the air; furthermore, the heat generated at thegasification furnace 2 due to production of the product gas iseffectively used for directly heating the excess nitrogen gas, and thetemperature of the drying gas is raised to a usable temperature bymixing the excess nitrogen gas and the air. Therefore, high-temperature,low-oxygen-concentration drying gas can be ensured without consumingfuel.

In this way, in the gasification furnace apparatuses Ga and Gb of thepresent invention described above, because the excess amount of nitrogengas generated at the air separator 3 for producing the product gas atthe gasification furnace 2 is used effectively and, furthermore, becausethe heat held by the gasification furnace 2 is also effectively used,the low-oxygen-concentration gas for drying the pulverized gas can beobtained without requiring fuel. As a result, in the gasificationfurnace apparatuses Ga and Gb equipped with the coal pulverizer 1 thatobtains the pulverized coal by pulverizing highly pyrophoric, low-gradecoal, the low-oxygen-concentration drying gas, which is required whenproducing the pulverized coal, can be obtained without having to providethe combustion furnace 4 that generates combustion gas by using fuel.

Incidentally, in the above-described embodiment, although thegasification furnace apparatuses Ga and Gb have been described as beingchemical gasification furnace apparatuses, the present invention is notlimited thereto, and it should be naturally appreciated that applicationto other types of gasification furnace apparatuses without sources oflow-oxygen-concentration drying gas is possible.

Note that, the present invention is not limited to the above-describedembodiment, and appropriate alterations are permissible within a rangethat does not depart from the gist of the present invention.

REFERENCE SIGNS LIST

-   1 Coal pulverizer-   2 Gasification furnace-   3 Air separator-   Air heater-   Ga, Gb Gasification furnace apparatus

1. A gasification furnace apparatus comprising: a coal pulverizer thatproduces pulverized coal by pulverizing coal; an air separator thatseparates air into oxygen gas and nitrogen gas; and a gasificationfurnace into which the pulverized coal and the oxygen gas are introducedto produce product gas, wherein, by receiving a supply of excessnitrogen gas from the air separator, the air diluted with nitrogen isused as a source of low-oxygen-concentration gas for drying thepulverized coal, and a heater that heats the source oflow-oxygen-concentration gas to a temperature at which drying can beperformed is provided.
 2. A gasification furnace apparatus according toclaim 1, wherein the heater performs heat exchange between the vaporwhose temperature is raised upon passing through the gasificationfurnace and the source of low-oxygen-concentration gas to achieve thetemperature at which drying can be performed.
 3. A gasification furnaceapparatus according to claim 1, wherein the heater is the gasificationfurnace, which raises the temperature of the excess nitrogen gas thatpasses therethrough.